Voice coil for loud speakers



NOV. 6, 1956 ss N 7 2,769,942

VOICE COIL. FOR LOUD SPEAKERS 2 Sheets-Sheet l Filed Nov. 26, 1954INVENTOR. W?

Nov. 6, 1956 J. A. HASSAN VOICE COIL FOR LOUD SPEAKERS 2 SheetsSheet 2Filed Nov. 26, 1954 BY 7 IIZ2TOR I M 004 tends to move said voice coilthe 2,769,942 VOICE COIL FOR LOUD SPEAKERS Joseph A. Hassan, Weymouth,Mass., assignor of one-half to Fauthal A. Hassan, Weymouth, Mass.

Application November 26, 1954, Serial No. 471,202 2 Claims. (Cl.317-158) its excursion, keeps within an effective influence of themagnetic flux, especially when reaches the voice coil. Since the lowfrequency current greatest distance, my invention is particularlyeffective in this respect.

To accomplish this, said coil winding, extending along the length of thecoil form, is shorter than that commonly same length, being three layersthick, hence the resistance remains, at least, the same as in atwo-layer, coil winding of greater length on said form.

The foregoing and other objects which the nature of the invention isbetter understood may be fall within the scope of my claims.

In the drawings:

Fig. 1 is a longitudinal, sectional view of a ducing device having myvoice coil.

Fig. 2 is an enlarged, fragmentary, sectional view showing the voicecoil in normal position in said device.

Fig. 3 is a view similar to- Fig. 2; but showing the voice coil in anactuated position therein.

Fig. 4 is a top plan view of my voice coil.

Fig. 5 is a fragmentary, elevational view, showing a free end of thevoice coil wire with a flattened portion.

Fig. 6 is a longitudinal, sectional view of a modified form of voicecoil.

Fig. 7 is a longitudinal, sectional view fied form of voice coil.

Fig. 8 is a perspective View of the voice coil shown in Fig. 7.

Fig. 9 is a longitudinal sectional view of another modified form ofvoice coil.

Fig. 10 is a sectional view taken on line 1010 of Fig. 9.

Fig. 11 is an enlarged, sectional view taken on line 11-11 of Fig. 9.

As illustrated, my device has the usual instrumentalities to actuate orvibrate the diaphragm. These include the usual magnetic frame it)embodying at its upper part an inwardly extending portion 12. A fieldpole 14, having a base portion 16, is attached to said frame 10 andextends upwardly therefrom. A voice coil has a form 18 around which is acoil winding 26. This form 18 is split or separated as at 22.

Said coil winding starts with a free end 24, then the sound proofanother modi- Wire is wound around said form 18 until three layers ofwire 25 are provided. At the completion of this third and outside layerthis leaves another free end 26 at the lower or opposite end of thevoice coil from that of said free end 24. A portion of this free end 26is then flattened, as at 28, until it is of no more thickness, andpreferably of lesser thickness, than that of the coil form 18, hence itstwo thinner sides of said flattened portion are and outer peripheralsurfaces thereof, hence it takes no space outside the voice coil and hasnoeflect on the magnetic flux.

The foregoing arrangement enables the use of a shorter voice coil whileusing the same length of winding wire, thus keeping the whole voicecoil, during actuation, within effective influence of said flux. Thismaintains the volume satisfactorily constant and the sounds distinctive.

In Figure 6 of the drawings, 1 show a modified form of voice coil inwhich the coil winding of wire starts with a free end 39 and the windingcontinues for two layers of wire terminating in another free end 32extending from thesecond layer. Then a separate wire 36, starting with afree end 34 is wound outside the other latter wire being or shallowspace left between the outer parts of the encircling wire portions thatlie alongside and in contact with each other. Said wires are, of course,circular in cross This enables the use of three layers of wire; withouttaking as much space as the three layers shown in Figures 1, 2 and 3, sothat the voice coil is of somewhat reduced thickness.

A free end 37 of the wire of the third layer extends beyond an end ofthe coil winding and a flattened portion 38 thereof extends between thetwo ends of said form 18 in the manner previously explained, beingwithin the inner and outer peripheral surfaces thereof. This free end 37is soldered, as at 39, to said free end 32 that extends from said secondlayer, thus connecting the second material such as aluminum or othermetal, being split as at 43. The winding starts with the usual free end44 and the other free end 46 from the third layer of wire is soldered,as at 48, to said conductive said coil form 42 beyond said coil windingat an opposite end of the coil winding to said soldering point 48. Saidsoldering point 52 is located at an opposite side of said split fromsaid point 48 so that the metal coil form 42 between said solder pointsprovides the maximum travel for the electrical current while serving asa conductor in place of wire.

My device has the usual parts, including a compliance spider 56surrounding and attached to the upper part of said coil form 18. Aconical diaphragm its smaller end to said voice coil form 18. Outsidesaid diaphragm 58 is the usual diaphra m support 60 of genof said spider56 is attached.

in Fig. 9 of the drawings, instead of a voice coil form, I provide acombination of an independent voice coil winding 66 and a connector 68,the latter commencing where the coil winding 66 ends, being attached toan end of said Winding by cement. The diaphragm 58 will connect to theopposite end of said connector 68. The coil winding 66 is similar tothat shown in Fig. l; but without a coil form. This assembly of aplurality of layers of wire, having an interior space, preferably has anindentation 70 forcibly made therein, surface of the coil winding 66 andextending inwardly from one end to the other.

A portion of a free end 72 of the voice coil winding 66 is flattened asat 74, and laid in said indentation 70 and cemented thereto. The size ofthe indentation 70 relative to said flattened portion 74 is such thatthe latter is wholly received within said indentation, thus notoccupying any space in the magnetic gap. The free end 72 is thenattached to said connector 68, as by cement, or laid alongside thereof,and extends between opposite ends thereof and beyond.

This arrangement eliminates the voice coil form within the coil winding66, hence use of a smaller magnetic gap is possible to movably receivesaid coil winding 66 and said connector 68 beyond it. This reduction inthe size of the magnetic gap results in a stronger magnetic flux, for agiven magnet size.

What I claim is:

1. A voice coil comprising a non-magnetic form having a split thereinextending the length thereof, and a coil winding embodying wireextending around said form in two layers, said coil winding having afree end extending from an inner said layer and another free endextending from the second of said layers, a separate wire, providing athird layer, outside said second layer embodying a free end extendingbetween two portions of said form opposite commencing at the outer saidsplit and beyond, and electricity conducting means uniting both saidlatter free ends, said wire forming said three layers beingsubstantially circular in cross section, said separate wire lying partlyin the dips between two portions of wire that are alongside of and incontact with each other and that form said first two layers.

2. A voice coil comprising a non-magnetic form having a split thereinextending the length thereof, and a coil winding embodying wireextending around said form in two layers, said coil winding having afree end extending from an inner said layer and another free endextending from the second of said layers, a separate wire, providing athird layer, outside said second layer embodying a free end extendingbetween two portions of said form opposite said split and beyond andWithin the interior and exterior peripheral surfaces thereof, andelectricity conducting means uniting both said latter free ends, saidwire forming said three layers being substantially circular in crosssection, said separate wire lying partly in the dips between twoportions of wire that are alongside of and in contact with each otherand that form said first two layers.

References Cited in the file of this patent UNITED STATES PATENTS1,869,230 Tirnmons July 26, 1932 1,976,895 Snell Oct. 16, 1934 2,084,945Cornwell June 22, 1937 2,503,243 Cohen Apr. 11, 1950

